Embryo structure of Metcalfia and four species of Danthonia was studied. Following Reeder's scheme2), the embryo features of Metcalfia can be expressed as F+FP, and those of Danthonia as P-PF. These observations indicate that Metcalfia is quite distinct from the Danthonieae and should be placed in the Aveneae. The morphological properties of Metcalfia suggest that it is probably one of the most primitive festucoid genera.
The mature embryos of Cuscuta japonica, C. australis and C. chinensis are of structures of yellow cylinder, tapering toward the apex and spirally coiled. They bear a few plumular scales but no cotyledon. Lacking in the opposite leaves, the phyllotaxis of seedlings is distichous from the first and it gradually changes to spiral. Such a phyllotaxis should be called “Cuscuta-type”.
The duration of mitotic cycle and its three subperiods were measured by means of autoradiographic technique in root tip cells of Luzula purpurea (n=3). Thymidine-H3 (0.5-2.0μc/ml) was used for the labeling of DNA and was supplied to the roots for 1/2hr. After labeling, roots of the seedling were allowed to grow in the absence of labeled thymidine for periods up to 26hrs. The average time of mitotic cycle was determined to be 17.0hrs. in duration, the time of DNA synthesis 6.5hrs., presynthetic interphase 6hrs., postsynthetic interphase 4.5hrs.
1. Nothoscordum inutile was found to have 2n=16, and n=8 chromosomes. The complements were classified into three groups from a morphological point of view. 2. Out of 2n=16 chromosomes, four are nucleolar chromosomes, showing a heterochromaty. The heterochromatic region is located in the proximal ends of short arms of two chromosomes and in the distal ends of short arms of the other two. 3. The former chromosomes are furnished with large centromeres which are nucleolus organizing regions.
1) The karyotype analysis is carried out on nine species, one subspecies of Cacalia and Syneilesis. 2) There can be found that Syneilesis palmata (or Cacalia krameri) is karyologically different from the member of Cacalia (Bucacalia) and shows to have a specific constitution of the karyotype. 3) All the members of the genus Cacalia studied are classified into four types from the view point of the karyotype and Sect. Bucacalia is subdivided into three different subtypes. 4) Most of the genus Cacalia studied have, in general, characteristic asymmetrical karyotypes which are derived from the higher polyploidization of a basic number of ten (or five). 5) A close phylogenic relationship between C. hastata ssp. farfaraefolia and C. hastata ssp. orientalis is suggested. 6) The relation between the genus Cacalia and the genus Syneilesis is discussed from the karyological stand point.